Research results will contribute to world's treasure of knowledge in the field of water protection. Integrated evaluation of wastewater impact on surface and ground water was developed. Research in the field of metrology in chemistry incorporated development of basic concepts of traceability and measurments uncertainity in water and wastewater analysis. Research in the field of biological wastewater treatment contributes more information about kinetic of degradation of different substances in batch (SBR) and biofilm reactors. Our results has shown that hydrodynamic conditions play an important role in the operation of biofilm reactors at low Reynolds numbers. The research of excess sludge treatment from biological wastewater treatment plants has shown that the combination of anaerobic and aerobic thermophilic treatment of sludge in two stages was much more efficient than conventional sludge treatment, especially mesophilic anaerobic sludge treatment. An integrated approach, which involves chemical-specific measurments as well as "whole-toxicity" assessment, was introduced for more effective effluent quality characterisation. A methodology of toxicity reduction evaluation (TRE) was developed. We participated in international projects COEPT (Comparability of the operation and evaluation protocols of European proficiency testing schemes, Project reference: G7RT-CT-2002-05108), project Quality Infrastructure - Proficiency tests (EuropeAid/113266/C/SV/ZZ, EU, EFTA, Danish Technological Institute) and EUROMET/EURACHEM Project 693 (Support Programme for Metrology in Chemistry in EU Candidate Countries, TrainMic-Training of Trainers). Research in the field of atmospheric chemistry contributes new information to understanding the chemical transformation of SO2 and NOx in the polluted boundary layer. First of all, it contributes knowledge to understanding the complex reaction mechanisms taking place in the atmospheric aqueous phase (hase, fog, clouds). Reactivity studies of aerosol particles and their role in atmospheric processes are particularly important because little is known about this topic. Aerosol particles are involved in different problems in the environment (e.g. diseases of respiratory systems, climate changes). They are involved in numerous atmospheric processes and play an important role in the formation of secondary aerosol material, particularly under high humidity conditions. These processes can change the composition as well as the character of aerosols. In particular, the more acidic character is important because of the increased health risk and damage caused to all environments. Results of our investigations have been published in journals with high impact factors for this field (J. Atmos. Chem.; Atmos. Environ.). The group was involved in EUROTRAC-2 (EUREKA Project 1489 "Transport and Chemical Transformation of Environmentally Relevant Trace Constituants in the Troposphere over Europe") untill end of 2002. We are currently taking part in the COST 633 ("Particulate Matter: Properties and Health Effects") project. We are also involved in ESF Scientific Programme with numerous partners from Europe. This programme is focused on "Interdisciplinary Tropospheric Research: from the Laboratory to Global Change" (INTROP). The progeamme strated in January 2004 and will last 5 years. We are already involved, as associate users, in an UE project within the sixth framework: Integrated Project EUROCHAMP (Integration of European Simulation Chambers for Investigating Atmospheric Processes), which has already been selected by European Commission for funding.